Continuous break spinning method and apparatus

ABSTRACT

A YARN FORMED AND TWISTED IN A ROTARY SPINNING CHAMBER OF LIKE TWISTING MEANS, IT IS TRANSPORTED TO TAKE UP MEANS. A SECTION OF THE TRANSPORTED YARN IS TENSIONED, PREFERABLY BY FRICTION MEANS, SO THAT SUCCESSIVE SECTIONS AND THE ENTIRE YARN ARE PERMANENTLY STRETCHED AND DEFORMED WHEREBY THE TENSILE STRENGTH OF THE YARN IS INCREASED.

United States Patent Inventors Josef Ripka;

Jan Junek; Milan Marsalek; Frantisek Hortlik, Usti Nad Orlici, Czechoslovakia Appl. No. 802,799 Filed Feb. 27, 1969 Patented June 28, 1971 Assignee Vyzkumny Ustar Barlnasky Usti,

Orlici, Czechoslovakia. Priority Feb. 2 811968 Czechoslovakia 1548-68 CONTINUOUS BREAK SPINNING METHOD AND APPARATUS 29 Claims, 28 Drawing Figs.

US. Cl 57/34, 57/58.89, 57/156 Int. Cl D01h 1/12, DOlh 5/00 Field of Search 57/34, 36,

Primary Examiner-Donald E. Watkins Attorney-Michael S. Striker 1 ABSTRACT: A yarn formed and twisted in a rotary spinning chamber or like twisting means, it is transported to take up means. A section of the transported yarn is tensioned, preferably by friction means, so that successive sections and the entire yarn are permanently stretched and deformed whereby the tensile strength of the yarn is increased.

PATEN'TEflJuNzalgn 3,587,219

SHEET 3 OF 9 INVENTO T05 GIT?! K: 14m 1/ By HIM) IMDQL Eli FDA/ 775!!! #04721! L CONTINUOUS BREAK SPINNING METHOD AND APPARATUS BACKGROUND OF THE INVENTION The present invention is concerned with a break spinning method and apparatus which produces a yarn of increased tensile strength as compared with standard yarn produced by break spinning.

The term "break spinning" is used in the present application to describe operations in which yarn is formed of fibers or a roving and twisted in a rotary spinning chamber vortex tube, twist tube, needle spinning basket or like yarn forming and twisting device.

In accordance with the prior art, the formation and twisting of the yarn by the twisting means is independent of the winding up of the yarn, and the continuity of the flow of material between drafting and combing apparatus and the twisting means is interrupted.

A twisting takes place during rotation of the spinning chamber or like device under the action of the centrifugal force. Even if the rotary speed of the twisting means is high, and the centrifugal force is great, the spinning tension at the outlet of the spinning and twisting device is low in order to prevent frequent breakages of the yarn. As a result, the yarn produced by break spinning has a lower tensile strength than a yarn manufactured on a ring spinning machine. Another disadvantage of break spinning is the need for a higher twist of the yarn for obtaining optimal tensile strength. To obtain such high twist, the yarn must be maintained at a low spinning tension, causing imperfect connection between the fibers within the yarn. The conditions are further aggravated by the fact that the yarn tension reaches its maximum at the outlet from the spinning and twisting device, and is lowest at the point where the yarn is formed.

The need for a higher twist also reduces the yarn output obtained by break spinning since the yarn production does not rise in direct proportion with the increase of the rotary speed of the yarn, and as compared with spindle revolutions in conventional machines.

The above-described disadvantages of break spinning have detrimentally affected the sale of break spun yarn which, due to their lower tensile strength, cannot be substituted for conventionally produced yarn.

A SUMMARY OF THE INVENTION it is one object of the invention to overcome the disadvantages of known break spinning methods and apparatus, and to improve a break spun yarn to have a high tensile strength.

Another object of the invention is to stretch and permanently deform the twisted yarn in order to increase its tensile strength.

Another object of the invention is to provide a continuous break spinning arrangement in which the twisted yarn is stretched for increasing its tensile strength and directly transported to takeup means by which it is wound.

with these objects in view, a continuous break spinning method according to the invention comprises the steps of forming a yarn, twisting the yarn, withdrawing and transporting the twisted yarn, and tensioning the transported yarn in a zone along the length thereof. Due to the tensioning in this zone, successive sections of the yarn, and thereby the entire yarn, are permanently stretched and deformed whereby the tensile strength of the yarn is increased.

A break spinning apparatus, according to one embodiment of the invention, comprises twisting means, such as a rotary spinning chamber, for forming and twisting a yarn, and having an outlet for the same; means for transporting the twisted yarn, preferably including a pair of withdrawal rollers and a takeup means for winding up the yarn; and stretching means extending along a zone of predetermined length so that successive sections of the transported yarn are tensioned and stretched in the stretching zone. In this manner, the entire yarn is continuously permanently stretched and deformed, and the tensile strength of the yarn is increased.

In the preferred embodiment of the invention, the stretching means include friction means engaging the yarn section to stretch the transported yarn.

In order to obtain a favorable breakage rate outside of the twisting means, the yarn is subjected in the stretching zone to a tension which is lower than the minimum resistance of the stretched and strengthened yarn.

in order to improve the stability of the spinning and twisting operations, it is advantageous to stretch and permanently deform the yarn in a zone located between the outlet of the twisting means and the rollers by which the yarn is withdrawn from the twisting means and transported to takeup means.

However, a breakage detector may be provided between the stretching means and the transporting rollers, or between the twisting means and the stretching means.

In accordance with another embodiment of the invention, the stretching means is provided between withdrawal rollers and takeup means so that the conventional withdrawing of the twisted yarn from the outlet of the twisting means is not disturbed, which is advantageous for improving existent break spinning apparatus in accordance with the invention.

If the type of twisted yarn requires a gentle action, continuous tension is applied in the stretching zone. However, in a modification, spaced portions of the yarn section in the stretching zone are stretched, while other portions of the respective yarn section are not stretched to a degree producing a permanent deformation of the yarn.

in order to obtain a yarn of very uniformed quality along the length thereof, alternating of fluctuating components of the yarn tension in the stretching zone are attenuated so that the magnitude of the relative amplitude of these components is reduced.

in accordance with the preferred embodiment of the apparatus of the invention, the stretching means include friction means through which the respective yarn section is drawn by transporting means which may be the withdrawal rollers of the twisting means, or the takeup means by which the yarn is wound up.

it is advantageous to construct the friction means of a stationary friction means and a biassed movable friction means, and to operate a breakage indicator when the biassed movable friction means is displaced due to a yarn breakage. A sensing means may also be inserted into the stretching zone for sensing a section of the yarn passing through the same, and to operate a breakage indicator when the yarn section breaks in the stretching zone.

The biassed movable friction means yields and again advances when fluctuations of the tension occur so that due to the resistance of the biassing means, for example springs, the fluctuations are attenuated.

Each of the stationary and movable friction means includes at least one and preferably a plurality of cylindrical friction pins defining a tortuous path for yarn section in the stretching zone. Preferably, adjusting means are provided for adjusting the relative position of the stationary and movable friction means to obtain a desired degree of tension and stretching of the yarn. The adjusting means may also be used to place the movable friction means in a position in which the yarn can be easily threaded between the stationary and movable friction means.

In accordance with the modified embodiment of the invention which is advantageous due to its easy operation and for adaptability for use in a system for collectively starting break spinning operations and for automatic control of yarn breakages, the movable spring biassed friction means can be moved by operating means to an inoperative position. The operating means may include a manually operated cam, a pneumatic or hydraulic distant, or an electromagnet.

Another embodiment of the invention results in a very compact structure requiring little space. in this construction, a tortuous channel or tube is directly connected with the outlet of the twisting means so that the yarn section in the channel or tube is frictionally breaked, stretched, and permanently deformed.

By applying the method and apparatus of the invention, a yarn of great tensile strength and having excellent uniformity of mass and of qualitative characteristics along the length thereof, is obtained. The minimum yarn resistance is increased as compared with conventional yarn produced by the twisting means, and irregularities of the tensile strength are eliminated.

Due to the improvement of the yarn according to the present invention, fabrics manufactured of improved yarn have also improved quality and performance.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is the schematic diagram illustrating an apparatus of the invention in accordance with one embodiment;

FIG. 2 is a schematic diagram illustrating a modification of the embodiment of FIG. 1;

FIG. 3 is a schematic diagram illustrating another modification of the embodiment of FIG. 1;

FIG. 4 is a schematic diagram illustrating a further modification of the embodiment of FIG. I;

FIG. 5 is a diagram graphically showing continuous variations of the tension applied to the yarn;

FIG. 6 is a schematic perspective view'illustrating a friction means for continuously stretching the yarn in accordance with one of the graphs of FIG. 5;

FIG. 7 is a diagram graphically indicating stepwise increase of the yarn tension;

FIG. 8 is a friction means for stepwise stretching the yarn in accordance with one of the graphs shown in FIG. 7;

FIG. 9 is a diagram graphically illustrating the increase of initial tension fluctuations in the stretching zone, and the attenuation of the amplified tension fluctuations;

FIG. 10 is a perspective view illustrating an embodiment of the stretching means of the invention which obtains attenuation of amplified tension fluctuations, and also serves as a breakage detector;

FIG. 11 is a fragmentary perspective view illustrating another embodiment of the stretching means combined with the sensing means of a breakage detector;

FIG. 12 is a sectional view illustrating another embodiment of the stretching means of the invention having attenuation transfer characteristics;

FIG. 13 is a sectional view illustrating another embodiment of the stretching means provided with means for adjusting the friction resistance and tension;

FIG. 14 is a sectional view illustrating a frictional stretching means including two brake members;

FIG. 15 is a schematic diagram illustrating another embodiment of the invention provided with stretching and tensioning rollers;

FIG. 16 is a fragmentary sectional view illustrating another embodiment of the stretching means provided with mechanical operating means for placing the device in a threading position;

FIG. 17 is a sectional view illustrating another embodiment of the stretching means provided with pneumatic or hydraulic means for placing the device in a threading position; 1

FIG. 18 is a sectional view illustrating another embodiment of the stretching meansprovided with electromagnetic operating means for placing the device in a threading position;

FIG. 19 is a fragmentary schematic sectional view illustrating another embodiment of the stretching means provided with a tortuous outlet channel;

FIG. 20 is a schematic side view illustrating another embodiment of the stretching means in the form of a helical outlet tube;

FIG. 21 is a fragmentary sectional view illustrating a twisting means in the form of a rotary spinning chamber having a vertical axis;

FIG. 22 is a fragmentary sectional view illustrating a twisting means in the form of a rotary spinning chamber having a horizontal axis;

FIG. 23 is a schematic side view illustrating a twisting means in the form of a needle spinning basket;

FIG. 24 is a fragmentary schematic sectional view illustrating the twisting means in the form of a vortex tube;

FIG. 25 is a fragmentary elevation, partially in section, schematically illustrating twisting means in the form of a twist tube in an electrostatic spinning system;

FIG. 26 is a sectional view illustrating a twisting means in 1 the form ofa spinning cylinder having an inner fiber collecting surface provided with needles;

FIG. 27 is a fragmentary perspective schematic view illustrating a twisting means in the form ,of a spinning cylinder for intermittent spinning, with a skew opening for axial withdrawal of the yarn; and

FIG. 28, shown on the sheet of FIG. 9, is a fragmentary sectional view illustrating a twisting means in the form of a twist tube for pneumatic spinning.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the embodiments of FIGS. 1 to 4, a yarn spun and twisted by the twisting means 1 is withdrawn from the outlet of the twisting means by a pair of transporting and withdrawing rollers 4 and supplied to takeup means 5 by which the yarn is wound up. In accordance with the invention, a section of the yarn between twisting means 1 and takeup means 5 is stretched in a stretching zone by stretching means 2 which increase the tension in successive yarn sections passing in the stretching zone through the stretching means. Successive yarn sections are stretched, so that the entire twisted yarn is stretched and permanently deformed before being wound up by the takeup means 5. 1

FIGS. 1 to 4 schematically illustrate a tortuous path for the yarn section in the stretching means 2, and other constructions of the stretching means 2 form part of the present invention.

In the arrangement of I FIGS. 1, 2 and 3, the stretching means 2 directly receives the twisted yarn from the outlet of twisting means 1, and the yarn is drawn through the stretching means 2 by the transporting rollers 4. In the embodiment of FIG. 2, the transporting rollers 4 directly follow the outlet of the twisting means 1 to withdraw the twisted yarn 3 from the outlet of twisting means 1 in the usual manner, and the yarn is transported through the stretching means by the takeup means 5.

The term twisting means is used in the present application to define spinning and twisting means of the type used for break spinning, as illustrated in FIGS. 21 to 28 which show a stretching means 2 directly following a twisting means corresponding to the embodiment of FIG. 1. However, each of the twisting means shown in FIGS. 21 to 28, can also be used in the embodiments of FIGS. 2 to 4.

FIG. 21 illustrates the spinning and twisting chamber of the type in which fibers combed by a roller out of a roving are deposited by the action of the centrifugal force on an inner circular surface of spinning chamber 11 whereby a yarn is formed which is bent substantially to pass through the outlet tube of the spinning chamber while being twisted. FIG. 22 illustrates a similar twisting chamber 12 in which a newlyformed and twisted yarn is bent almost before being discharged through the outlet.

FIG. 23 illustrates a spinning and twisting means in the form of a needle basket 13 by which the yarn 3 is twisted.

FIG. 24 illustrates a spinning and twisting means 14 in the form of a vortex tube.

FIG. 25 illustrates twisting means in the form of an electrostatic spinning system having a twist tube.

FIG. 26 illustrates twisting means 16 in the form of a spinning chamberhaving needles on the fiber collecting inner surface.

FIG. 27 illustrates twisting means 17 in the form of a spinning cylinder for intermittent spinning with an axial skew opening serving as outlet for the yarn.

FIG. 28 illustrates a twisting means 18 in the form of a pneumatic spinning device with a twist tube.

The spinning and twisting devices illustrated in FIGS. 21 to 28 are known and have not been described in detail because the specific constructions are not part of the present invention.

Referring again to FIG. 3, in'this modification of the apparatus of FIG. 1, a breakage detector 6 is located between the stretching means 2 and the transporting and withdrawal rollers 4. In the modification of FIG. 4, the breakage detector 6 is located between the outlet of twisting means 1 and the stretching means 2. In the embodiments of FIGS. 3 and 4, a linkage 7 connects the breakage detector 6 with operating means 8 which act through a linkage 9 on the stretching means to move the same between inoperative and operative positrons.

The method and apparatus of the invention are based on'the principle that an irreversible permanent deformation can be imparted to a break spun yarn in which the fiber arrangement is imperfect. In order to obtain an improved arrangement of the fibers within the yarn, tensile forces are applied to successive sections of the yarn to obtain a corresponding stretching by the fast application of a substantial force so that irreversible permanent displacements of the fibers take place at almost the same speed. A comparison of the structure of a conventional yarn produced, for example on a ring frame, with a conventional break spun yarn clearly shows that the break spun yarn, produced without a spindle, has an arrangement of fibers inferior to the fiber arrangement of the yarn produced on a ring frame. Therefore, the quality of the break spun yarn can be improved by the present invention which obtains a more perfect arrangement of the fibers by stretching and permanently deforming successive sections of the yarn.

In accordance with the inventionthe quick application of a strong tensioning force to the yarn is obtained by transporting the newly spun and twisted yarn at a predetermined speed through a stretching zone in which its longitudinal tension is increased by stretching means 2. It has been found by tests that the best effect is obtained when the zone in which the longitudinal yarn tension is increased is provided directly following the outlet of the spinning and twisting means 1, as shown'in FIGS. 1, 2 and 3, and FIGS. 21 to 28. The advantage of this arrangements resides not only in that the yarn is continuously tensioned, but also in that no other operation or machine is required. Since the yarn 3 at the outlet of the twisting means 1 has a certain longitudinal spinning tension, it is advantageous to increase the tension by stretching means 2 in the form of friction means which act on successive yarn sections to increase the tension in the same within a zone of predetermined length so that the tension is sufficient to produce the permanent tensile deformation and stretching of the yarn. By suitably selecting the frictional resistance and the speed and force of the transporting means 4 or 5, a permanent stretching and an improved arrangement of the fibers in the yarn is obtained. The permanently stretched yarn is less expansible in longitudinal direction, and its tensile strength is improved as compared with a yarn produced by spinning and twisting means 1 without further treatment in the stretching zone.

It is evident that the longitudinal tension in the yarn cannot be increased to a value at which the frequency of breakages would be increased due to the increased tension. However, considering that due to the increase in tension, the yarn is permanently deformed to obtain a greater tensile strength, it is possible to define the upper limit of the tension increase by the condition that the increase of the tension in the stretching loom must not exceed the minimum resistance of the improved and strengthened yarn at this point.

When the breakage detector 6 for yarn 3 is interposed between twisting means 1 and withdrawal rollers 4, as shown in FIGS. 3 and 4, then the yarn 3 passes through the breakage detector 6 before or after being permanently stretched.

By increasing the longitudinal tension of yarn 3 in the stretching zone of the stretching means 2, which preferably includes friction surfaces engaging the yarn, the initial tension of the yarn is increased.

FIG. 5 graphically illustrates an initial tension 8,, a final tension S, after passage of yarn 3 through the tensioning and stretching means 2, and four graphs 101 to 104 indicating the functions of the gradual increase of the tension along the length L of the stretched yarn section. S, and 8, represent mean values of the yarn tension. Graph 101 shows a linear increase, graph 102 shows a rapid increase then a slower increase, graph 103 has a substantial exponential curve and indicates first a slower increase and then a more rapid increase, and graph 104 indicates a varying rate of the increase of the yarn tension.

FIG. 6 illustrates a tensioning and stretchingmeans 2 including a cylinder 21 about which yarn 3 is guided in helical windings by yarn guides 31 and 32 which are axially spaced from each other along cylinder 21. In this arrangement, the increase of the axial tension of yarn 3 due to the action of friction forces according to Eulers Law, occurs in accordance with an exponential function depending on the bending angle of the yarn and the friction coefficient. Friction cylinder 21 produces a gradual increase of the tension in the stretched yam section in accordance with the graph 103 in FIG. 5.

As shown in FIG. 7, the mean or average value of the initial tension S, can be stepwise increased in the tensioning loom of the stretching means 2. The graph 105illustrates an increase of the yarn tension in two steps, and the graph 106 an increase of the yarn tension in three steps. The pennanent deformation of the yarn is consequently obtained by applying tension several times, with intermediate periods in which no tension is applied which is advantageous for yarn made of certain fibers which are subjected to short tensile shock forces.

FIG. 8 illustrates a frictional tensioning and stretching means for producing intermittent tensioning forces. The stretching means is fork shaped and has two cylindrical friction pins 211, and a shaft permitting angular displacement of the same. Friction pins 211 have recesses 33 for axially guiding the yarn 3 which is laid in loops about friction pins 211. The yarn 3 is supplied to the lower friction pin 211 and sharply bent to partly surround the same before being laid about the upper friction pin 211. When the yarn is pulled through the device, the tension in the respective yarn section is increased in accordance with an exponential function, as graphically illustrated by the arising portions. of the graph 106 in FIG. 7. The yarn approaches one roller 211 to make a first turn about the same whereby the tension in the yarn is exponentially increased. The yarn then passes through an area of constant tension between the rollers 211 and approaches the other roller to make a second tum then passes through an area of constant tension, makes a third turn and passes through a third area of constant tension after which the yarn makes a final turn.

In FIGS. 5 and 6, it was assumed that the initial spinning tension of the yarn at the outlet of twisting means 1 is constant. Actually, the initial tension S, obtained by spinning and twisting is variable and the initial tension fluctuates depending on fiber conditions in the spinning and twisting means. It can be assumed that the initial tension has a constant mean value increased by fluctuating additional values at different frequencies and amplitudes.

FIG. 9 shows a mean value S, of the initial tension which actually fluctuates in accordance with an assumed sinusoidal function illustrated by graph 107. Graph 107 has an amplitude A,. Due to the tensioning in the stretching zone the tension is increased as indicated by the graph 108 to a mean value S, having peaks and valleys representing the amplified initial tension. The amplitude of the tension fluctuations is A,. The tension fluctuations occur within a time T which depends on the speed of movement of the yarn.

Coefficient of the tension increase Z can be defined as the ratio of mean values of the initial tension before the yarn enters the tensioning zone, and the mean value of the yarn tension at the end of the-tensioning zone.

The tension fluctuations can be attenuated as shown by graph 109, as will be explained hereinafter, but for the amplified tension fluctuations 108 the following equation is valid:

and the relative amplitude a, can tion:

be expressed by the equa- Without attenuation, the individual components maintain the magnitude of the relativeamplitude, and a,=a,. Assuming that attenuation is obtained so that the tension fluctuations of the 'yarn in the tensioning zone have the amplitude A it follows so that regarding the relative amplitudes, the following relation is valid:

wherein a is the relative amplitude of the attenuated tension fluctuations 109. A suitably constructed tensioning and stretching member, preferably including friction means, obtains an attenuation for diminishing relative amplitudes of the fluctuating components of the longitudinal tension of the yarn.

FIG. 12 illustrates a stretching means with attenuation transfer characteristics. Fixed cylindrical friction pins 214 are secured to a support 25. A friction member 251 is secured to a lever 252 mounted for angular movement in the vertical plane on a pivot means 253. A weight 254 is slidable along lever 252. During operation, the tensioned yarn 3 holds friction member 251 and lever 252 in a position depending on the tension in the yarn, while weight 254 presses friction member 251 downward into engagement with yarn 3 until the forces are in equilibrium.

The bending angle of the yarn 3 at friction member 251 is such that the sum of the initial and final tensions produce equal turning moments about pivot 253 acting in opposite directions on lever 252. When the tension of yarn 3 is in creased at the outlet of the twisting means, the angle of yarn 3 at friction member 251 is varied, and the biasing means 254,251 displaceuntil the forces are in equilibrium again, and a new position of the yarn and friction member 251 causes an increase of the tension at the end of the stretching device 25 as compared with the tension of the yarn discharged by the twisting means, but the amplification is less than without the yielding biassing means 254,251. The weight and position of the mass 254 can be selected to obtain best attenuation of tension fluctuations depending on the particular characteristics of the fibers and yarn produced by the spinning and twisting means.

The embodiment of the stretching means shown in FIG. is a friction device 23 including stationary friction means 231, and angularly movable friction means 232. Friction means 231 has a set of friction pins 212 mounted on a shaft which supports bearings on which friction pins 212' are supported for angular movement. Yarn guides 33 and 34 guide yarn 3 to alternately pass along a tortuous path about friction pins 212 and 212. An arm 61 is secured to the bearing portions of the movable friction means 232 and connected by a spring 60 to a stationary support 10 so that pins 212' are biassed to turn away from pins 212 to produce a friction force on yarn 3. As in the embodiment of FIG. 11, an equilibrium is obtained between the biassing force of spring 60 and'the tension forces acting on yarn 3, and when the initial yarn tension fluctuates, and is increased, the tension applied by the friction device 23 to the yarn is attenuated.

A contact 62 is secured to arm 61 and corporates with the stationary contact 63 on a support 6. Conductors 621 and 631 connect contacts 62 and 63 with the circuit of breakage detector 6.

During normal operation, the torque exerted by tension spring 60 on arm 61 is in equilibrium with the torque produced by the yarn tension acting on pins 212 and 212', and the position of the movable friction means 232 is such that contacts 62 and 63 are separated and the breakage detector is disconnected. If the yarn 3 breaks, biassing spring 60 turns the movable brake means 232 to a position-in which contacts 62 and 63 close so that breakage detector 6 is actuated, and a signal is given to conductors 621,631 to an indicating means, or to means for stopping the operations.

Referring now to FIG. 11, the stretching means 24 has cylindrical friction pins 213 for guiding the yarn 3 along a tortuous path. A sensing feeler 64 is secured to an arm 65 pivotally mounted on a shaft 651, and is urged by gravity to engage a tensioned section of yarn 3. Arm 65 has a contact 62 cooperating with another contact 63 of a breakage detector 6 which is connected by conductors 621 and 631 to indicator means for indicating the yarn breakage, or for stopping the machine.

In FIG. 13, the stretching means 26 includes three friction pins 215, and two friction members 216 which are mounted on a u-shaped support 262 whose legs are guided in bearings 263. A threaded spindle 262 is screwed into a stationary support plate 10 so that the relative position between the movable friction means 262,216 and the stationary friction means 215 can be adjusted until yarn 3 is bent selected angles to reproduce the desired frictional resistance and tension, resulting in stretching of the yarn to permanently deform the same to a desired degree. When the operation of screw 262, friction member 216 are raised, the tension and stretching are reduced.

FIG. 14 illustrates a stretching device in which a disc brake 27 frictionally engages yarn 3. A stationary friction plate 271 abuts a head of a screw 273, while a movable friction member 271 is displaceable in axial direction on the same. A spring 274 abuts friction member 272 and an adjustable nut and washer 275 so that yarn 3 is frictionally clamped between the friction surfaces 276 and 277. The friction force applied by friction members 271,272 can be adjusted by nut 275 until yarn 3 is stretched and permanently deformed to a desired degree when transported by transporting means 4,5.

A different type of stretching means 28 is used in the arrangement of FIG. 15. The twisted yarn is withdrawn from twisting means 1 and transported by transporting roller 4 to the takeup rollers 5. The stretching means 28 is disposed between transporting rollers 4 and twisting means 1 and includes a first pair of rollers 281 having a peripheral speed v and a second pair of rollers 282 having a peripheral speed v The speed v;, of transporting rollers 4 is greater than the speed v of rollers 282 which is greater than the speed v, of rollers 281. Consequently, the yarn is stretched between rollers 281 and rollers 4 by a considerably increased axial tension. It is possible to operate the device in such a manner that yarn 3 is withdrawn by roller 281 of the twisting means 1 through the breakage detectors 6 at the speed v,, which is gradually accelerated to a speed of 1.06 v,, whereupon the yarn 3 is wound up by the takeup means 5 approximately at the same speed. It

is possible to drive only one pair of the two pairs of rollers 281,282 so that friction is applied to yarn 3.

The stretching means ,29 of FIG. 16 is a combination of the embodiments of FIGS. 10, 12 and 13. Stationary cylindrical friction pins 217 formastraight row, and friction members 218 mounted on a lever 291 define with friction pins 217, a tortuous path for yarn 3. Lever 291 is turnable about the pivot 296 and is biassed by spring 811 which abuts the frame portion. Consequently, when the yarn tension is increased, lever 291 is raised against the action of the biassing spring 811 until an equilibrium is again obtained whereby tension oscillations are attenuated. The desired normal operative position of friction members 218 can be adjusted by turning the handle 813 of a circular cam 812 which is mounted on a pin 814 and en gages the end portion 293 of lever 291 to block downward movement of lever 291 in all turned positions so that friction members 218 ca'nnot move downward out of the adjusted position under the action of springs 811 to undesirably increase the tension applied to yarn 3. In the illustrated position, friction members 218 are in the lowest possible position, and lever 291 rests on cam 812 in the region of its smallest eccentricity. 1 7

When cam 812 is turned [80 out of the illustrated position so that its maximum eccentricity is effective, lever 29] and friction members 218 are raised to a position in which the yarn can be easily threaded between friction members 218 and friction pins 217. When friction members 218 are located above the level of friction pins'217, no friction forces are applied to yarn 3 and the stretching device is inoperative.

The stretching means 29 shown in FIGS. 17 and 18 operate in the same manner as the stretching means 29, shown in FIG. 16. However, the embodiment of FIG. 17 is provided with pneumatic or hydraulicoperating means, and the device of FIG. 18 is provided with electromagnetic operating means to replace the mechanical operating means 812,813 of FIG. 16.

In the embodiment of FIG. 17, lever 291 is mounted on a pivot 292 and has an end portion 293 secured by holding member 821 to the piston rod 822 of a piston 823 located in a cylinder 828 in which a spring 825 is disposed to act on piston 823 so that friction members 218 have a normal operative position illustrated in the drawing. When compressed air or liquid is admitted into the chamber 828 of cylinder 824 through inlet 826, piston 823 is raised against the action of spring 825, while air is discharged out of cylinder 824 to the outlet 827. By operation of a valve, not shown, controlling inlet 826, friction members 218 can be first raised to an adjusted position in which the friction forces acting on yarn 3 are reduced, and further raised to a position located above the level of friction pins 217, permitting easy threading of yarn 3 into the device 29.

In the embodiment of FIG. 18, lever 295 is connected with friction members 218 and mounted between the ends thereof on a pivot 296. The arm 297 of the double arm lever 295 is secured by a holding means 831 connected with a spring 832 which is secured to the support 83. In the illustrated normal operative position of the apparatus, tension spring 832 holds friction members pressed against yarn 3, and an adjustable stop, not shown, may be provided for limiting downward movement of friction members 218 with lever 295. When the tension fluctuates in the yarn, spring 832 is expanded so that tension fluctuations are attenuated.

An electromagnet has a core 833 and a winding 834 with leads 835. When a switch, not shown, is closed, electromagnet 833,834 is energized and attracts the end portion 297 of lever 295 which serves as an armature so that lever 295 is turned in clockwise direction and friction members 218 are raised to a level higher than the level of friction members 217, permitting easy treading of yarn 3.

The stretching device shown in FIG. 19 has a tortuous channel with projections 202 and recesses 201. Yam 3 frictionally engages the projections on opposite sides of the channel so that a frictional resistance against the pull of the transporting means is produced and the yarn is stretched. The end of the channel is directly connected with the outlet of the spinning and twisting means 1.

The embodiment of the stretching means shown in FIG. 20 has a tortuous, preferably helical tube 203 directly connected to the outlet of a spinning and twisting means 1 so that the yarn 3 moves along a tortuous path in tube 203 and is frictionally braked and accordingly stretched.

In the embodiment of FIG. 20, a bending angle of almost 900 is obtained so that the frictional resistance against the transporting pull is high.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of break spinning arrangements differing from the types described above.

While the invention has been illustrated and described as embodied in a break spinning method in which the spun and twisted yarn is tensioned and stretched to obtain a permanent deformation resulting in higher tensile strength due to a rearrangement of the fibers forming'theyarn, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

We claim:

1. A continuous break spinning method comprising the steps of forming a yarn of fibers; twisting the newly formed yarn; withdrawing and transporting the newly twisted yarn; and tensioning the transported yarn in a zone along the length thereof so that successive sections of the yarn, and thereby the entire yarn, are permanently stretched and deformed whereby the tensile strength of the yarn is increased.

2. The method of claim 1 wherein the twisted yarn directly enters said zone from twisting means and is transported through the same.

3. The method of claim 1 wherein said twisted yarn is directly withdrawn from twisting means by transporting means, and transported by the same into said zone; and comprising winding up of the stretched yarn.

4. The method of claim 1 wherein said step of tensioning comprises frictionally braking the yarn section moving through said zone.

5. The method of claim 1 wherein the tension applied to said yarn in said zone is below the tensile strength of the yarn.

6. The method of claim 1 wherein the drafting tension applied to said yarn in said zone is gradually increased.

7. The method of claim 1 wherein the tension applied to said yarn in said zone is stepwise increased.

8. The method of claim 1 wherein the tension applied to said yarn in said zone is at least partially adapted to the varying tensile strength of individual yarn sections.

9. A continuous break spinning method, comprising the steps of forming yarn; twisting the yarn; withdrawing and transporting the twisted yarn; and tensioning the transported yarn in a zone along the length thereof by frictionally braking spaced portions of said yarn moving through said zone whereby other portions of said yarn move through said zone without being tensioned so that successive sections of the yarn, and thereby the entire yarn, are permanently stretched and deformed whereby the tensile strength of the yarn is increased.

10. A continuous break spinning method comprising the steps of forming a yarn; twisting the yarn; withdrawing and transporting the twisted yarn; and tensioning the transported yarn in a zone along the lengththereof by frictionally braking the yarn in said zone by biassed means so that when initial tension fluctuations of said twisted yarn are amplified in said zone, the amplified tension fluctuations are attenuated by yielding of said biassing means, so that successive sections of the yarn, and thereby the entire yarn, are permanently stretched and deformed whereby the tensile strength of the yarn is increased.

1]. Break spinning apparatus comprising, in combination, twisting means for forming and twisting a yarn, and having an outlet for the twisted yarn; means for transporting said twisted yarn; and stretching means between said outlet and said transporting means extending along a zone so that successive sections of the transported yarn are tensioned and stretched in said zone whereby the entire yarn is continuously permanently stretched and deformed and the tensile strength of the yarn is increased. I

12. Apparatus as claimed in claim 11 wherein said stretching means include first and second pairs of stretching rollers respectively located at the beginning and end of said zone; wherein said second pair of stretching rollers has a higher peripheral speed than said first pair, and a smaller peripheral speed than the transporting speed of said takeup means.

13. Apparatus as claimed in claim 11 wherein said stretching means include friction means engaging said yarn section. v

14. Apparatus as claimed in claim 11 wherein said trans porting means comprise means for withdrawing said twisted yarn from said outlet and for supplying the same to said takeup means.

15. Apparatus as claimed in claim 14 said stretching means are located between said transporting means and said outlet.

16. Apparatus as claimed in claim 14 wherein said stretching means are located between said transporting means and said takeup means.

17. Apparatus as claimed in claim 14 wherein said stretching means include friction means located between said transporting means and said outlet so that said transporting means withdraw the twisted yarn from said outlet through said friction means.

18. Apparatus as claimed in claim 11 comprising sensing means located in said zone for sensing said yarn section; and means controlled by said sensing means for indicating a yarn breakage.

19. Apparatus as claimed in claim 11 wherein said stretching means include stationary friction means, and biassed movable friction means forming a path for said yarn section so that upon yarn breakage said biassed movable friction means makes a movement; and means controlled by said biassed movable friction means to indicate a yarn breakage.

20. Apparatus as claimed in claim 11 wherein said stretching means include a stationary friction means, and biassed movable friction means forming a tortuous path for said yarn section so that when initial tension fluctuations of said twisted yarn'are amplified in said zone by the transporting of said yarn section through said stationary and movable friction means, said biassed movable friction means yield so that the amplified tension fluctuations are attenuated.

21. Apparatus as claimed in claim 11 wherein said stretching means include a pair of friction brake plates between which said yarn section is located, and resilient means for pressing said friction brake plates against said yarn section.

22. Apparatus as claimed in claim 11 wherein said stretching means include movable friction means having an operative position forming a tortuous path for said yarn section so that the same is braked and stretched, and an inoperative position in which yarn can be threaded through said friction brake means; and control means for moving said friction means between said inoperative and operative positions, and for holding said friction means in said positions.

23. Apparatus as claimed in claim 11 wherein said stretching means include stationary friction means and movable friction means forming a path for said yarn section, said movable friction means having an operative position in which said path is tortuous, and an inoperative position in which said path is wide and straight for threading of a yarn between said stationary and movable friction means, and biassing means for urging said movable friction means to said operative position;

comprisin control means including a control member connected wit said movable friction means for moving the same between said positions and for holding the same in said positions, respectively; and operating means for said control member.

24. Apparatus as claimed in claim 11 wherein said stretching means includes a tortuous channel directly following said outlet for frictionally braking said yarn section.

25. Apparatus as claimed in claim. 11 wherein said stretching means includes a tortuous tube having one end connected with said outlet and forming a tortuous channel for frictionally braking said yarn section.

26. .Apparatus as claimed in claim 11 wherein said stretching means include friction means engaging said yarn section, said friction means including means about which said yarn of said section is at least partly wound.

27. Apparatus as claimed in claim 26 wherein said body means include a plurality of bodies, and means for adjusting the relative position of said bodies.

28. Apparatus as claimed in claim 11 wherein said twisting means has an outlet channel; and wherein said stretching means include friction means in said outlet channel for braking and stretching said yarn section.

29. Apparatus as claimed in claim 28 wherein said outlet channel is helical. 

